U.S. patent number 7,832,380 [Application Number 12/361,112] was granted by the patent office on 2010-11-16 for marine fuel system with an ullage control device.
This patent grant is currently assigned to Brunswick Corporation. Invention is credited to Amir Abou Zeid, Troy J. Kollmann, Brian L. Merten, Timothy S. Reid, Michael A. Torgerud.
United States Patent |
7,832,380 |
Abou Zeid , et al. |
November 16, 2010 |
Marine fuel system with an ullage control device
Abstract
A marine engine fuel system provides a low pressure lift pump to
draw fuel from a fuel tank and cause the fuel to flow into a
reservoir and a high pressure fuel pump which draws fuel from the
reservoir and provides it to a fuel rail. An inlet conduit of the
high pressure fuel pump is provided with a primary and a secondary
opening. The secondary opening can be an orifice formed through a
wall of the inlet conduit. The secondary opening is positioned,
relative to the primary opening, at a location which assists in
controlling the fuel level within the reservoir and the quantity of
gaseous fuel contained within an ullage above the liquid pool of
fuel.
Inventors: |
Abou Zeid; Amir (Waupun,
WI), Reid; Timothy S. (Fond du Lac, WI), Kollmann; Troy
J. (Mt. Calvary, WI), Torgerud; Michael A. (Mt. Calvary,
WI), Merten; Brian L. (St. Cloud, WI) |
Assignee: |
Brunswick Corporation (Lake
Forest, IL)
|
Family
ID: |
43065766 |
Appl.
No.: |
12/361,112 |
Filed: |
January 28, 2009 |
Current U.S.
Class: |
123/519 |
Current CPC
Class: |
F02M
37/14 (20130101); F02M 37/18 (20130101); F02M
37/0052 (20130101); F02M 37/103 (20130101); F02M
37/0082 (20130101); F02M 33/08 (20130101) |
Current International
Class: |
F02M
33/04 (20060101); F02M 33/02 (20060101) |
Field of
Search: |
;123/519,520,518,517,509,456,457
;137/565.01,565.17,565.29,565.33,571,255 ;440/88F |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gimie; Mahmoud
Attorney, Agent or Firm: Lanyi; William D.
Claims
We claim:
1. A marine engine fuel system, comprising: a reservoir configured
to contain a quantity of fuel; a first fuel pump having a first
inlet and a first outlet; a first inlet conduit connected in fluid
communication with said first inlet; a second fuel pump having a
second inlet and a second outlet; a second inlet conduit connected
in fluid communication with said second inlet; a primary opening
formed in said second inlet conduit; and a secondary opening formed
in said second inlet conduit, said primary and secondary openings
being disposed within said reservoir, said secondary opening being
disposed at a higher elevation than said primary opening, wherein
fuel is supplied in a forward flow direction to said engine, and
said second fuel pump is downstream of said first fuel pump along
said forward flow direction.
2. The fuel system of claim 1, wherein: said second fuel pump is
disposed within said reservoir.
3. The fuel system of claim 2, wherein: said first fuel pump is
disposed within said reservoir.
4. The fuel system of claim 1, wherein: said first inlet conduit is
connected in fluid communication with a fuel tank of a marine
vessel; and said first outlet is connected in fluid communication
with said reservoir.
5. The fuel system of claim 1, wherein: said second inlet conduit
is connected in fluid communication with said reservoir; and said
second outlet is connected in fluid communication with a fuel
rail.
6. The fuel system of claim 1, wherein: said primary opening is
located at a distal end of said second inlet conduit.
7. The fuel system of claim 6, wherein: said secondary opening is
an orifice located between said primary opening and said second
inlet.
8. The fuel system of claim 1, wherein: said second inlet conduit
is positioned to dispose said primary opening within liquid fuel
and to dispose said secondary opening in fluid communication with
vaporous fuel when both liquid and vaporous fuel exist within said
reservoir.
9. The fuel system of claim 1, wherein: said second inlet conduit
is positioned to dispose said primary opening closer to said second
outlet than to said second inlet.
10. A marine engine fuel system, comprising: a reservoir configured
to contain a quantity of fuel; a first fuel pump having a first
inlet and a first outlet, said first fuel pump being disposed
within said reservoir; a first inlet conduit connected in fluid
communication with said first inlet; a second fuel pump having a
second inlet and a second outlet, said second fuel pump being
disposed within said reservoir; a second inlet conduit connected in
fluid communication with said second inlet; a primary opening
formed in said second inlet conduit; and a secondary opening formed
in said second inlet conduit, said primary and secondary openings
being disposed within said reservoir, said secondary opening being
disposed at a higher elevation than said primary opening, wherein
fuel is supplied in a forward flow direction to said engine, and
said second fuel pump is downstream of said first fuel pump along
said forward flow direction.
11. The fuel system of claim 10, wherein: said first inlet conduit
is connected in fluid communication with a fuel tank of a marine
vessel; and said first outlet is connected in fluid communication
with said reservoir.
12. The fuel system of claim 11, wherein: said second inlet conduit
is connected in fluid communication with said reservoir; and said
second outlet is connected in fluid communication with a fuel
rail.
13. The fuel system of claim 12, wherein: said primary opening is
located at a distal end of said second inlet conduit.
14. The fuel system of claim 13, wherein: said secondary opening is
an orifice located downstream from said primary opening and
upstream from said second inlet.
15. The fuel system of claim 10, wherein: said second inlet conduit
is positioned to dispose said primary opening within liquid fuel
and to dispose said secondary opening in fluid communication with
vaporous fuel when both liquid and vaporous fuel exist within said
reservoir.
16. The fuel system of claim 10, wherein: said second inlet conduit
is positioned to dispose said primary opening closer to said second
outlet than to said second inlet.
17. A marine engine fuel system, comprising: a reservoir configured
to contain a quantity of fuel; a first fuel pump having a first
inlet and a first outlet; a first inlet conduit connected in fluid
communication with said first inlet; a second fuel pump having a
second inlet and a second outlet; a second inlet conduit connected
in fluid communication with said second inlet; a primary opening
formed in said second inlet conduit; and a secondary opening formed
in said second inlet conduit, said primary and secondary openings
being disposed within said reservoir, said secondary opening being
disposed at a higher elevation than said primary opening, said
second inlet conduit being positioned to dispose said primary
opening within liquid fuel and to dispose said secondary opening in
fluid communication with vaporous fuel when both liquid and
vaporous fuel exist within said reservoir, wherein fuel is supplied
in a forward flow direction to said engine, and said second fuel
pump is downstream of said first fuel pump along said forward flow
direction.
18. The fuel system of claim 17, wherein: said second fuel pump is
disposed within said reservoir; and said first fuel pump is
disposed within said reservoir.
19. The fuel system of claim 17, wherein: said first inlet conduit
is connected in fluid communication with a fuel tank of a marine
vessel; said first outlet is connected in fluid communication with
said reservoir; said second inlet conduit is connected in fluid
communication with said reservoir; and said second outlet is
connected in fluid communication with a fuel rail.
20. The fuel system of claim 17, wherein: said second inlet conduit
is positioned to dispose said primary opening closer to said second
outlet than to said second inlet.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally related to a marine fuel system
and, more particularly, to a fuel system that provides primary and
secondary openings in a fuel conduit to allow fuel vapor to be
removed from the cavity of a fuel reservoir.
2. Description of the Related Art
Those skilled in the art of marine propulsion systems are aware of
many different types of fuel systems. Some fuel systems use fuel
vapor separators which are vented while others use unvented
reservoirs. Some systems incorporate lift pumps and high pressure
pumps within the structure of a fuel reservoir while others place
these pumps outside the fuel reservoir. Certain marine propulsion
systems use separate pumps to lift fuel from a fuel tank and to
pressurize the fuel and induce it to flow to a fuel injection
system. In all types of marine propulsion systems, it is beneficial
to control the accumulation of fuel vapor within the system and to
moderate the temperature of the fuel under a wide variety of
circumstances.
U.S. Pat. No. 4,844,043, which issued to Keller on Jul. 4, 1989,
describes an anti-vapor lock carbureted fuel system. It includes a
first crankcase pressure driven fuel pump supplying fuel from a
remote fuel tank to a vapor separator, and a second crankcase
pressure driven fuel pump supplying vapor free fuel from the vapor
separator to the carburetors of the engine. In combination, a
squeeze bulb and one-way check valve supply fuel from the remote
fuel tank directly to the carburetors for starting the engine.
U.S. Pat. No. 4,848,283, which issued to Garms et al. on Jul. 18,
1989, discloses a marine engine with combination vapor return,
crankcase pressure, and cooled fuel line conduit. A marine
propulsion system includes a two-cycle water cooled crankcase
compression internal combustion engine including a vapor separator,
a remote fuel tank, and a fuel pump in the tank for delivering fuel
to the engine in response to crankcase pulse pressure. A
combination conduit between the fuel tank and the engine includes a
first passage communicating crankcase pulse pressure from the
engine to the fuel pump in the tank, a second passage supplying
fuel from the pump in the tank to the engine, a third passage
returning fuel vapor from the vapor separator at the engine back to
the tank, a fourth passage supplying cooling water from the engine
towards the tank, and a fifth passage returning water from the
fourth passage back to the engine.
U.S. Pat. No. 4,856,483, which issued to Beavis et al. on Aug. 15,
1989, discloses a vacuum bleed and flow restrictor fitting for fuel
injected engines with vapor separators. The fitting is provided in
the vapor supply line. The fitting has a first reduced diameter
passage providing a vacuum bleed orifice passage partially venting
vacuum from the induction manifold to atmosphere, to limit peak
vacuum applied to the vapor separator from the induction manifold.
The fitting has a second reduced diameter passage providing a flow
restrictor passage limiting the volume of flow of fuel vapor from
the vapor separator to the induction manifold.
U.S. Pat. No. 4,876,993, which issued to Slattery on Oct. 31, 1989,
discloses a fuel system with a vapor bypass of oil-fuel mixer
halting oil pumping. The fuel delivery system has a vapor separator
connected to prevent excess oil in the mixture as fuel runs out.
The vapor separator has a fuel inlet receiving fuel from the tank,
a fuel outlet delivering fuel to the fuel inlet of the oil-fuel
mixer, and a vapor outlet delivering vapor or air through a bypass
connection to the suction intake side of a fuel pump and bypassing
the mixer.
U.S. Pat. No. 5,389,245, which issued to Jaeger et al. on Feb. 14,
1995, discloses a vapor separating unit for a fuel system. It has
particular application to a fuel system for a marine engine. The
vapor separating unit includes a closed tank having a fuel inlet
through which fuel is fed to the tank by a diaphragm pump. The
liquid level in the tank is controlled by a float-operated valve.
An electric pump is located within the vapor separating tank and
has an inlet disposed in the tank and an outlet connected to a fuel
rail assembly of the engine.
U.S. Pat. No. 5,647,331, which issued to Swanson on Jul. 15, 1997,
describes a liquid cooled fuel pump and vapor separator. The fuel
pump is housed in an aluminum body module formed by two iso-pods
open end to open end to provide a multi-cavity module housing of
heat conductive material. The pump inlet faces downwardly in one of
the cavities and a small clearance volume directly surrounds the
pump casing which, in one embodiment, is filled with liquid fuel
and in another with cooling water.
U.S. Pat. No. 5,832,903, which issued to White et al. on Nov. 10,
1998, discloses a fuel supply system for an internal combustion
engine. It has an electronically controlled fuel injection system
which eliminates the need for a vapor separator. The system pumps
an excessive amount of fuel through a plumbed fuel supply loop and
cools recirculated fuel to cool all the components in the plumbed
fuel supply loop. Recirculated fuel flows from the pressure
regulator to the water separating fuel filter as does make-up fuel
from a fuel tank. The fuel stream from the water separating fuel
filter flows to the low pressure side of the fuel pump which pumps
the fuel through the plumb fuel supply loop.
U.S. Pat. No. 5,855,197, which issued to Kato on Jan. 5, 1999,
describes a vapor separator for fuel injected engines. A compact
vapor separator for a fuel injection system reduces the size of the
fuel system mounted on the side of an outboard engine. The girth of
the outboard motor's power head consequently is decreased. In one
embodiment, the vapor separator employs a plurality of rotary vein
type pumps. The pumps are sized to produce a sufficient flow rate
and fuel pressure, while minimizing power consumption.
U.S. Pat. No. 5,908,020, which issued to Boutwell et al. on Jun. 1,
1999, describes a marine fuel pump and cooling system. It comprises
a fuel pump, a fuel filter axially mounted directly below and
around the lower portion of the fuel pump, and a spiral-wound fuel
line composed of a heat conductive material mounted concentric to
the upper portion of the fuel pump, minimizing the space required
for installation.
U.S. Pat. No. 5,915,363, which issued to Iwata et al. on Jun. 29,
1999, describes a fuel supply system for an engine powering an
outboard motor. The system includes a pump for supplying fuel from
a tank to a vapor separator. Another pump delivers fuel from the
vapor separator to at least one charge former for supplying fuel to
the combustion chambers of the engine. The fuel supply system
includes a mechanism for reducing the transmission of vapor to the
pump which delivers fuel to the charge formers.
U.S. Pat. No. 6,006,705, which issued to Kato et al. on Dec. 28,
1999, describes a fuel injection system. It includes a main fuel
source and a pump for delivering fuel from the main fuel source
through a fuel filter to a vapor separator. Fuel is supplied from
the chamber by a high pressure pump through a fuel rail to one or
more fuel injectors. Undelivered fuel is returned to the vapor
separator through a return line.
U.S. Pat. No. 6,076,509, which issued to Kyuma on Jun. 20, 2000,
describes a fuel supply apparatus of an outboard motor. It
comprises a vapor separator for removing bubbles in the fuel, a
float type bubble discharge valve which is provided for the vapor
separator and adapted to be closed when a fuel level in a fuel tank
rises, and a negative pressure opening type valve connected to a
downstream side of the bubble discharge valve so as to be opened
upon reception of an intake negative pressure of the engine.
U.S. Pat. No. 6,216,672, which issued to Mishima et al. on Apr. 17,
2001, describes a fuel supply system of an outboard motor. It
comprises a fuel tank in which a fuel is stored, a low pressure
fuel filter and a low pressure fuel pump connected to the fuel tank
through a fuel supply hose, a vapor separator connected to the low
pressure fuel pump through a low pressure fuel hose, a high
pressure fuel pump disposed inside the vapor separator, a pressure
regulator disposed inside the vapor separator, a fuel hose having
one end connected to the high pressure fuel pump, and a branch pipe
incorporated on the way of the fuel hose and having one end
connected to the pressure regulator.
U.S. Pat. No. 6,253,742, which issued to Wickman et al. on Jul. 3,
2001, discloses a fuel supply method for a marine propulsion
engine. It uses a lift pump to transfer fuel from a remote tank to
a vapor separator tank. Only one level sensor is provided in the
vapor separator tank and an engine control unit monitors the total
fuel usage subsequent to the most recent filling of the tank. When
the fuel usage indicates that the fuel level in the vapor separator
tank has reached a predefined lower level, a lift pump is activated
to draw fuel from a remote tank and provide that fuel to the vapor
separator tank.
U.S. Pat. No. 6,257,208, which issued to Harvey on Jul. 10, 2001,
describes a marine vapor separator. A method of controlling fuel
temperature while supplying fuel from a fuel tank to an array of
fuel injectors of an internal combustion engine comprises the steps
of pumping the fuel with a high pressure pump, flowing the fuel
through a fuel line from the fuel tank to the high pressure pump,
and flowing the fuel through a vapor separator in the fuel line
between the tank and the high pressure pump.
U.S. Pat. No. 6,321,711, which issued to Kato on Nov. 27, 2001,
describes a fuel supply system for a direct injected outboard
engine. It includes a pump for supplying fuel from a tank to a
vapor separator. An electrical pump delivers fuel from the vapor
separator to a mechanical high pressure pump, which delivers fuel
under high pressure to a fuel manifold and further to a pair of
fuel rails. The fuel rails supply fuel to fuel injectors for
delivering fuel to the combustion chambers of the engine.
U.S. Pat. No. 6,428,375, which issued to Takayanagi on Aug. 6,
2002, describes a fuel cooling apparatus of an outboard motor. It
has a vapor separator, a fuel injector positioned to supply a fuel
from the vapor separator into the engine, a high pressure fuel pump
positioned in the vapor separator to feed the fuel under pressure
to the fuel injector, and a pressure regulator positioned in the
vapor separator to reduce a pressure of a return fuel, the fuel
cooling apparatus including a fuel cooler having fuel and cooling
water passages arranged side by side.
U.S. Pat. No. 6,553,974, which issued to Wickman et al. on Apr. 29,
2003, discloses an engine fuel system with a fuel vapor separator
and a fuel vapor vent canister. The system provides an additional
fuel chamber, associated with a fuel vapor separator, that receives
fuel vapor from a vent of the fuel vapor separator. In order to
prevent the flow of liquid fuel into and out of the additional fuel
chamber, a valve is provided which is able to block the vent of the
additional chamber.
U.S. Pat. No. 6,575,145, which issued to Takahashi on Jun. 10,
2003, describes a fuel supply system for a four cycle outboard
motor. It includes a fuel injection system that includes a fuel
pump, a plurality of fuel injectors, a fuel pump and a vapor
separator. The vapor separator is in communication with a fuel pump
and at least one fuel return line. The vapor separator includes a
vent for removing vapors from the fuel. The vapor separator also
includes a canister positioned within the vapor separator below the
vent. The canister includes hydrocarbon absorption media.
U.S. Pat. No. 6,679,229, which issued to Wada et al. on Jan. 20,
2004, describes a fuel supply apparatus for an outboard engine. To
improve a freedom of layout within a narrow cowling of an outboard
engine, achieve a reduction of manufacturing costs and an
improvement of a maintenance performance of a fuel filter, a fuel
supply apparatus in an outboard engine is structured such that fuel
within a fuel tank is supplied into a vapor separator via a to low
pressure fuel pump.
U.S. Pat. No. 6,698,401, which issued to Suzuki et al. on Mar. 2,
2004, describes a fuel supply control system for an outboard motor.
It regulates the fuel pressure to a vapor separator in a fuel
injection system by using a pressure relief valve that returns
excess fuel to the intake of the fuel pump. In order to permit
excess fuel flow without substantial excess in low speeds, the fuel
pump speed is regulated depending upon engine speed, fuel
temperature, and fuel pressure.
U.S. Pat. No. 6,918,380, which issued to Nomura on Jul. 19, 2005,
describes a fuel injection apparatus for a marine engine. To
provide a fuel injection apparatus preferable for a marine engine
which can prevent a metal soap from being generated in a motor
portion of a high pressure electric pump even when fuel containing
sea water is sucked into the electric pump, a high pressure
electric pump is provided with a pump portion and a motor portion
within a pump housing, the pump portion sucks fuel within a vapor
separator, high pressure fuel the pressure of which has been
increased by the pump portion is discharged through a periphery of
the pump portion.
U.S. Pat. No. 7,101,239, which issued to Torgerud et al. on Sep. 5,
2006, discloses a fuel filter located below an adapter plate of an
outboard motor. A marine propulsion device is provided with a fuel
filter that is connectable between a fuel tank and a fuel pump,
wherein the fuel filter is disposed below an adapter plate of the
marine propulsion device. The adapter plate is located between the
fuel filter and the engine so that the fuel filter is not located
under the cowl of the marine propulsion device where an engine is
housed.
U.S. Pat. No. 7,168,414, which issued to Harvey on Jan. 30, 2007,
describes a marine vapor separator with a bypass line. Liquid fuel
is to supplied to a marine engine from a fuel tank. The fuel first
passes through a water filter, a lift pump and is temporarily
deposited in a vapor separator where vapors given off from the fuel
are collected and vented. A high pressure pump withdraws liquid
fuel from the vapor separator and delivers it under pressure to an
engine injection system via a fuel delivery line.
U.S. Pat. No. 7,178,512, which issued to Merten on Feb. 20, 2007,
discloses a fuel system for a marine vessel with a gaseous purge
fuel container. A fuel container for a marine propulsion system is
provided with a pump and a hose connected to an outlet of the pump
and disposed within the cavity of the fuel container. The hose is
provided with an opening, formed through its wall, through which a
fluid can flow under certain circumstances. The opening is disposed
in an ullage within the container and allows gaseous elements to be
purged from the container when flow is induced from the container
back to a fuel reservoir.
U.S. Pat. No. 7,401,598, which issued to Ochiai on Jul. 22, 2008,
describes an outboard motor with forward air intake and air cooled
fuel pump. It comprises a cowling for covering an engine, a high
pressure fuel supply system, and a low pressure fuel supply system.
The high pressure fuel supply system can have a vapor separator
tank and a high pressure fuel pump. The low pressure fuel supply
system can have a low pressure fuel pump. A heat insulating
chamber, defined from a space for accommodating the engine, can be
formed within the cowling. The heat insulating chamber houses the
low pressure fuel pump and the fuel filter.
The patents described above are hereby expressly incorporated by
reference in the description of the present invention.
As described above, many different types of fuel supply systems are
known to those skilled in the art. It is important to control the
temperature of fuel that is drawn from a fuel tank and supplied to
an engine located under the cowl of an outboard motor. It is also
necessary to control the accumulation of fuel vapor within the
conduits and reservoirs of the fuel system. It would therefore be
significantly beneficial if a relatively simple system could be
provided which controls the amount of gaseous fuel vapor contained
within a fuel reservoir, which moderates the temperature of stored
fuel within the reservoir or which is recirculated by its
associated fuel pumps, and which separates fuel circulated by one
fuel pump from fuel circulated by the other fuel pump.
SUMMARY OF THE INVENTION
Various embodiments of the present invention will be described
below. Preferred embodiments of the present invention provide a
marine engine fuel system which comprises a reservoir configured to
contain a quantity of fuel, a first fuel pump having a first inlet
and a first outlet, a first inlet conduit connected in fluid
communication with the first inlet, a second fuel pump having a
second inlet and a second outlet, and a second inlet conduit
connected in fluid communication with the second inlet.
In one embodiment of the present invention, a primary opening is
foamed in the second inlet conduit and a secondary opening is
formed in the second inlet conduit. The primary and secondary
openings are disposed within the reservoir, with the secondary
opening being disposed at a higher elevation than the primary
opening. In certain embodiments of the present invention, the first
and second fuel pumps are disposed within the reservoir and at
least partially submerged within the quantity of fuel. The first
inlet conduit can be connected in fluid communication with a fuel
tank of a marine vessel and the first outlet can be connected in
fluid communication with the reservoir. The second inlet conduit
can be connected in fluid communication with the reservoir and the
second outlet can be connected in fluid communication with a fuel
rail of a marine engine. In one preferred embodiment of the present
invention, the primary opening is located at a distal end of the
second inlet conduit and the secondary opening is an orifice
located between the primary opening and the second inlet. In a
particularly preferred embodiment of the present invention, the
second inlet conduit is positioned to dispose the primary opening
within liquid fuel and to dispose the secondary opening within
vaporous fuel when both liquid and vaporous fuel exist within the
reservoir. In certain embodiments of the present invention, the
second inlet conduit is positioned to dispose the primary opening
closer to the second outlet than to the second inlet.
In one preferred embodiment of the present invention, it comprises
a water pump and a first heat exchanger having a first water
circuit which is connected in fluid communication with the water
pump and disposed in thermal communication with a first fuel
circuit. It also can comprise a second heat exchanger having a
second water circuit which is connected in fluid communication with
the water pump and disposed in thermal communication with a second
fuel circuit. The second fuel pump can be connected in fluid
communication with the second fuel circuit and the first fuel pump
can be connected in fluid communication with the first fuel
circuit. In a particularly preferred embodiment of the present
invention, the second water circuit is disposed in thermal
communication between the second fuel circuit and the quantity of
fuel within the reservoir and the first water circuit is disposed
in thermal communication between the first fuel circuit and the
quantity of fuel within the reservoir.
In a particularly preferred embodiment of the present invention,
the fuel system is configured to inhibit fuel from flowing into the
first inlet after it has flowed into the quantity of fuel within
the reservoir and to inhibit fuel from flowing into the quantity of
fuel within the reservoir after it has flowed out of the second
outlet. The first and second heat exchangers can be disposed within
the quantity of fuel within the reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully and completely understood
from a reading of the description of the preferred embodiment in
conjunction with the drawings, in which:
FIG. 1 is a schematic representation of a fuel system incorporating
several concepts of a preferred embodiment of the present
invention;
FIG. 2 is an isolated enlarged view of one heat exchanger used in a
preferred embodiment of the present invention;
FIG. 3 is an isometric view of a fuel system used in a preferred
embodiment of the present invention;
FIG. 4 illustrates a variation of the fuel system shown in FIG. 1
which is intended to improve the performance of a fuel system in
the event that the fuel in the fuel tank 80 is depleted; and
FIG. 5 illustrates another variation of the fuel system shown in
FIG. 1 which is generally similar to the variation shown in FIG. 4,
but with modifications to change the operating characteristics of
the fuel system in the event that the fuel in fuel tank 80 is
depleted.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Throughout the description of the preferred embodiment of the
present invention, like components will be identified by like
reference numerals.
FIG. 1 is a schematic representation of a fuel system for a marine
engine made in accordance with a preferred embodiment of the
present invention. It is intended to illustrate several of the
advantageous concepts embodied in applications of the present
invention. The fuel system comprises a reservoir 10 which is
configured to contain a quantity of fuel 12. As will be described
in greater detail below, two dashed lines, 14 and 16, are used to
represent two different hypothetical fuel levels which separate the
liquid fuel from the ullage 18 above the liquid fuel. A preferred
embodiment of the present invention further comprises a first fuel
pump 21 having a first inlet 31 and a first outlet 41. A first
inlet conduit 51 is connected in fluid communication with the first
inlet 31. A preferred embodiment of the present invention further
comprises a second fuel pump 22 having a second inlet 32 and a
second outlet 42. A second inlet conduit 52 is connected in fluid
communication with the second inlet 32. A primary opening 60 is
formed in the second inlet conduit 52. A secondary opening 62 is
also formed in the second inlet conduit 52. The primary and
secondary openings, 60 and 62, are disposed within the reservoir
10. The secondary opening 62 is disposed at a higher elevation than
the primary opening 60.
With continued reference to FIG. 1, a preferred embodiment of the
present invention further comprises a water pump 66, a first heat
exchanger 71 and a second heat exchanger 72. The first heat
exchanger 71 has a first water circuit which is connected in fluid
communication with the water pump 66 and disposed in thermal
communication with a first fuel circuit. The first water circuit
and the first fuel circuit will be described in greater detail
below. The second heat exchanger 72 has a second water circuit
which is connected in fluid communication with the water pump and
disposed in thermal communication with a second fuel circuit. The
first fuel pump 21 is connected in fluid communication with the
first fuel circuit and the second fuel pump 22 is connected in
fluid communication with the second fuel circuit.
With continued reference to FIG. 1, the first fuel pump 21 draws
fuel from a fuel tank 80 through the first inlet conduit 51 and
causes the fuel to flow through conduit 82 to a fuel inlet 84 of
the first heat exchanger 71. The fuel, in a particularly preferred
embodiment of the present invention, flows through an inner tube 86
which is disposed within an outer tube 88 which contains a flowing
volume of water in the annular space 90 between the inner and outer
tubes, 86 and 88. A pressure regulator 94 maintains the pressure in
conduit 96 at approximately 70 kPa in a preferred embodiment of the
present invention. If the pressure exceeds the regulated pressure,
the regulator 94 directs fuel back to the first inlet conduit 51
for recirculation by the first fuel pump 21 through the first heat
exchanger 71.
The water pump 66 draws water from a body of water in which the
marine propulsion system is used and causes that water to flow
through conduit 100 and the annular space 90 between the inner and
outer tubes, 86 and 88, of the first heat exchanger 71. This water
flows upwardly through the space 90 and away from the first heat
exchanger 71 through conduit 102. The fuel flowing out of conduit
96 into the reservoir 10 is regulated at approximately 70 kPa.
With continued reference to FIG. 1, the second fuel pump 22 draws
fuel from the quantity of fuel 12 within the reservoir 10 and
causes it to flow downwardly and through conduit 110 to an inlet
114 of the second heat exchanger 72. The second heat exchanger 72
comprises an inner tube 116 and an outer tube 118 which are
configured to provide the annular space 120 therebetween. The fuel
flows upwardly through the inner tube 116 and through conduits 122
and 124. Regulator 130 maintains the pressure within conduits 132,
122, and 124 at approximately 350 kPa. Excess fuel is conducted
through conduit 134 back to the inlet 32 of the second pump 22.
Water flowing through conduit 102, from the first heat exchanger
71, is directed to the annular space 120 and then through an outlet
tube 140 to be returned to the body of water from which it was
originally drawn by pump 66.
With continued reference to FIG. 1, several characteristics of a
preferred embodiment of the present invention can be seen. First,
the first and second fuel pumps, 21 and 22, are both disposed
within the reservoir 10. The first inlet conduit 51 is connected in
fluid communication with the fuel tank 80 of a marine vessel and
the first outlet 41 is connected in fluid communication with the
reservoir 10. The second inlet conduit 52 is connected in fluid
communication with the quantity of fuel 12 within the reservoir 10
and the second outlet 42 is connected in fluid communication with
the fuel rail 138 through the second heat exchanger 72. The primary
opening 60 is located at a distal end 150 of the second inlet
conduit 52 and the secondary opening 62, which is an orifice in a
preferred embodiment of the present invention, is located between
the primary opening 60 and the second inlet 32. The second inlet
conduit 52 is positioned to dispose the primary opening 60 within
the liquid fuel 12 and to dispose the secondary opening 62 in fluid
communication with vaporous fuel in the ullage 18 when both liquid
and vaporous fuel exist in sufficient quantities within the
reservoir 10. In a preferred embodiment of the present invention,
the secondary opening 62 is an orifice having a diameter of
approximately 0.036 inches. The primary opening 60 is larger and,
in a typical application of the present invention, is equal to the
inner diameter of the second inlet conduit 52 which is
approximately 0.25 inches. In certain embodiments of the present
invention, the physical location of the secondary opening 62, in
relation to the primary opening 60, is important because it serves
as a factor in the determination of the fuel level (e.g. 14 or 16)
within the reservoir 10. As is apparent to those skilled in the
art, several factors affect the level of the liquid fuel 12 within
the reservoir 10. Naturally, the pumping capacities of the first
and second fuel pumps, 21 and 22, the demand for fuel by the fuel
rail 138, and the fluid dynamics of the fuel flowing through the
numerous conduits, pumps, and heat exchangers will affect the
position of the fuel level (e.g. 14 or 16) within the reservoir 10.
However, an important factor in the determination of the size of
the ullage 18 relative to the size of the liquid fuel pool 12 is
the position of the secondary opening 62 relative to the reservoir
10 and relative to the primary opening 60. The orifice 62 is
smaller than the size of the primary opening 60 and it draws
gaseous vapor much more readily than liquid fuel. If the secondary
opening 62 is within the ullage 18, it will tend to draw vaporous
fuel from the ullage more readily than liquid fuel is drawn through
the primary opening 60. This result is due to the fact that a
gaseous fuel vapor is much more easily drawn into the second inlet
conduit 52 by the second fuel pump 22 than liquid fuel is drawn
upwardly through the second inlet 52. As a result, the orifice of
the secondary opening 62 serves to control the size of the ullage
18 and the position of the fuel level, 14 or 16, within the
reservoir 10. It has been determined that it is beneficial to
control the amount of vaporous fuel within the ullage 18 in order
to assure a consistent and reliable flow of liquid fuel through
conduit 124 to the fuel rail 138. However, it has also been
determined that it is beneficial to provide some minimal amount of
vaporous fuel in the ullage 18 and prevent the reservoir 10 from
being completely filled with liquid fuel. The location of the
orifice of the secondary opening 62 allows this control to be
maintained. Naturally, it should be understood that the position of
the orifice of the secondary opening 62 and its size in relation to
the primary opening 60 can vary significantly from one application
of the present invention to another. In a particularly preferred
embodiment of the present invention, the second inlet conduit 52 is
positioned to dispose the primary opening 60 closer to the second
outlet 42 of the second fuel pump 22 than to the second inlet 32.
In other words, in a preferred embodiment of the present invention,
the second fuel pump 22 is positioned in such a way that it causes
the flow of fuel in a downward direction, draws fuel through the
primary opening 60 at a region near the bottom of the reservoir 10,
and maintains the size of the ullage 18 through the advantageous
positioning of the secondary opening 62. Those skilled in the art
of marine fuel systems will appreciate the fact that the second
fuel pump 22 need not always be configured to pump fuel in a
downward direction. Similarly, the first fuel pump 21 need not pump
fuel in an upward direction in all embodiments of the present
invention. Similarly, the first and second fuel pumps, 21 and 22,
need not be disposed within the reservoir 10 in all applications of
the present invention.
With continued reference to FIG. 1, it can be seen that the first
water circuit of the first heat exchanger 71 comprises conduit 100,
the annular space 90, and the initial portion of conduit 102. It is
connected in fluid communication with the water pump 66 and is
disposed in thermal communication with a first fuel circuit that
comprises the inside of the inner tube 86, conduit 82, the first
fuel pump 21, and conduit 96. As described above, the pressure
regulator 94 also allows a certain quantity of fuel to be
recirculated back to the first inlet conduit 51 and the first inlet
31 of the first fuel pump 21. The second water circuit comprises
conduit 102, the annular space 120 between the inner 116 and outer
118 tubes of the second heat exchanger 72 and conduit 140 which
returns the water back to the body of water from which it was
drawn. The water drawn by the pump 66 is induced to flow upwardly
through the first heat exchanger 71 and then downwardly through the
second heat exchanger 72. This provides two counter flow heat
exchangers since the fuel flows downwardly through the first heat
exchanger 71 and upwardly through the second heat exchanger 72. In
FIG. 1, solid line arrows represent the flow of fuel and dashed
line arrows represent the flow of water. As will be described in
greater detail below, the first and second heat exchangers, 71 and
72, provide a significant benefit when they are disposed within the
reservoir 10 as in a preferred embodiment of the present invention.
The water flowing through the annular spaces, 90 and 120, of the
first and second heat exchangers, 71 and 72, removes heat from both
the inner tubes, 86 and 116, respectively, and from the quantity of
fuel 12 within the reservoir 10. This is illustrated in more detail
in FIG. 2.
FIG. 2 is an isolated view of the first heat exchanger 71. Although
not specifically indentified in FIG. 2, it should be understood
that the liquid fuel 12, described above in conjunction with FIG.
1, is in contact with a significant portion of the outer surface
160 of the outer tube 88. The larger solid line arrows in FIG. 2
illustrate the flow of fuel into the inlet 84 and downwardly
through the inner tube 86. The larger dashed line arrows in FIG. 2
illustrate the flow of water upwardly through the annular space 90
between the inner and outer tubes, 86 and 88. The smaller
horizontal arrows are used to illustrate the directions of heat
flow.
With reference to FIGS. 1 and 2, heat from the liquid fuel 12 in
the reservoir 10 flows radially inwardly through the walls of the
outer tube 88 toward the colder water flowing upwardly through the
annular space 90 of the first heat exchanger 71. As a result, the
continual flow of water through this annular space 90 removes heat
from the fuel 12 stored within the reservoir 10. In addition, heat
is conducted in a radially outward direction through the wall of
the inner tube 86 and into the stream of water flowing through the
annular space 90. This removes heat from the fuel flowing in the
first fuel circuit described above. As some of the fuel is
recirculated through the first fuel circuit and through the
regulator 94, it can be heated because it is continually moved by
the operation of the first pump 21. This heat is removed through
the walls of the inner tube 86. The liquid fuel 12 within the
reservoir 10 can absorb heat from surrounding components of the
engine of a marine propulsion system and, as a result, its
temperature can be increased. The first heat exchanger 71 removes
this heat from the pool of liquid fuel 12 in the reservoir 10 by
absorbing calories through the wall of the outer tube 88. It should
be understood that although FIG. 2 only shows the heat exchanger
71, the basic principles described above apply equally to the
second heat exchanger 72. Both of them are intended to absorb heat
radially inwardly from the pool of liquid fuel 12 and radially
outwardly from the fuel flowing through their respective fuel
circuits and through their respective inner tubes, 86 and 116.
With continued reference to FIG. 1, another important
characteristic of the present invention can be seen. The fuel
system of a preferred embodiment of the present invention is
configured to inhibit fuel from flowing into the first inlet 31 of
the first pump 21 after it has flowed into the quantity of fuel 12
within the reservoir 10. Although, as described above, the first
fuel circuit of the first fuel pump 21 recirculates fuel through
the regulator 94, it should be understood that fuel does not return
to the first inlet 31 of the first fuel pump 21 once it is
conducted into the pool of liquid fuel within the reservoir 10. As
a result, the fuel of the quantity of fuel 12 within the reservoir
10 is not pumped again after it is initially conducted into the
reservoir. In addition, the fuel system of a preferred embodiment
of the present invention is configured to inhibit fuel from flowing
into the quantity of fuel 12 within the reservoir 10 after it has
flowed out of the second outlet 42 of the second pump 22. This is
true even though, as described above, fuel is recirculated through
the regulator 130 within the second fuel circuit. As a result, the
pool of liquid fuel within the reservoir 10 is, essentially,
isolated from both the first and second fuel circuits of the first
and second pumps, 21 and 22. The fuel that flows into the quantity
of liquid fuel 12 from the first pump 21 does not return to the
first fuel circuit after this has occurred. In addition, fuel drawn
from the pool of liquid fuel 12 by the second pump 22 does not
return to the quantity of liquid fuel 12 subsequently. This
isolation between the first and second fuel circuits serves to
reduce the amount of heat put back into the pool of liquid fuel by
the pumps. Although both the first and second fuel pumps
continually recycle fuel through their first and second fuel
circuits, respectively, that recirculating fuel is immediately
cooled as it flows through the inner tubes, 86 and 116, of the
first and second heat exchangers, 71 and 72, respectively.
The basic principles of a preferred embodiment of the present
invention serve to improve the fuel system of a marine engine in
numerous ways. Not all of these characteristics are required in
every embodiment of the present invention, but they are all
intended to serve beneficial purposes. For example, the use of two
heat exchangers is significantly beneficial in maintaining the
temperature of the fuel within the fuel system. In addition, the
arrangement shown in FIG. 1 allows both heat exchangers to be
counter flow heat exchangers which improve their efficiency. In a
preferred embodiment of the present invention, both heat exchangers
are disposed within the reservoir 10 in order to allow heat to be
removed simultaneously from both the pool of liquid fuel 12 and
through the first and second fuel circuits. In addition, a
preferred embodiment of the present invention places both the first
and second fuel pumps within the reservoir 10. The respective
locations of the primary 60 and secondary 62 openings within the
second inlet conduit 52 allows for the control of the desired fuel
level, 14 or 16, and the limitation of the quantity of vaporous
fuel within the ullage 18. In addition, as will be described in
detail below in conjunction with FIG. 3, the overall configuration
of the present invention allows an efficient and compact packaging
of the two fuel pumps and two heat exchangers within a common
reservoir housing.
The position of the secondary opening 62, relative to the top of
the interior portion of the reservoir 10, will determine the size
of the ullage in combination with other variables relating to the
sizes, configurations, and relative positions of other components
of the fuel system. The location of the upper surface of the liquid
fuel, which is hypothetically represented by dashed lines 14 and
16, will vary as a function of dimension h (illustrated in FIGS. 4
and 5) which will be to described below. However, it should be
clearly understood that the size of the ullage relative to the
volume of liquid fuel within the reservoir 10 is also a function of
the pressure and temperature of the fuel within the reservoir, the
rate at which fuel is provided to the fuel rail 138, the rate at
which the fuel is drawn from the fuel tank 80, the relative flow
rates through the various conduits of the fuel system, and the
operating characteristics of the various regulators and check
valves within the fuel system as will be described in greater
detail below in conjunction with FIGS. 4 and 5. It should also be
understood that although the magnitude of dimension h is important
in determining the position of the upper surface of liquid fuel
(e.g. dashed lines 14 or 16, hypothetically), the size of the
ullage is also dependent on several other dimensions, positions,
and operational characteristics.
FIG. 3 is an isometric view of some of the components of a
preferred embodiment of the present invention. For purposes of
clarity, the housing container of the reservoir 10, illustrated in
FIG. 1, has been removed from the illustration in FIG. 3. However,
an O-ring 200 has been left in place to show the basic size of the
housing. The position and size of the O-ring 200 illustrates the
location and size of a mating face between a lower portion and an
upper portion of the housing of the reservoir 10.
With continued reference to FIGS. 1-3, and particularly to FIG. 3,
the first pump 21 and second pump 22 are illustrated with the two
heat exchangers, 71 and 72, positioned between them. It should be
understood that several components and structures have been removed
from the illustration in FIG. 3 in order to more clearly identify
the relative positions of other components that are more directly
related to a preferred embodiment of the present invention and
allow a more informative comparison between FIGS. 1 and 3. Some of
these components which are not shown in FIG. 3 provide fluid
connections between the illustrated components. However, by
comparing FIGS. 1 and 3, the overall fuel and water circuits can be
fully understood.
With continued reference to FIGS. 1 and 3, fuel is drawn upwardly
through the first inlet conduit 51 by the first pump 21. This fuel
flows through the first inlet 31 and out of the first outlet 41.
After flowing upwardly through the first pump 21, the fuel is
conducted to the inlet 84 of the first heat exchanger 71 and flows
downwardly through the inner tube 86. From there, it flows through
the regulator 94 and back to the first inlet 31. Water is conducted
upwardly through conduit 100 and into the annular space 90 of the
first heat exchanger 71. From there, it flows over to the annular
space 120 of the second heat exchanger 72. Illustrated in FIG. 3 is
the inner tube 116 of the second heat exchanger 72 and its outer
tube 118. This water then flows downwardly through the annular
space 120 and is returned to the body of water from which it was
drawn. With continued reference to FIGS. 1 and 3, fuel is drawn
upwardly into the primary opening 60 of the second inlet conduit 52
and into the second inlet 32 of the second fuel pump 22. This fuel
is pumped downwardly by the second fuel pump 22 and directed toward
the lower end of the inner tube 116 of the second heat exchanger
72. The fuel flows upwardly through the inner tube 116 and through
conduit 124 to the fuel rail 138. Regulator 130 controls the flow
of fuel through the second fuel circuit and uses intake manifold
pressure, through conduit 210, as a reference pressure in order to
regulate the pressure in the fuel rail relative to manifold
pressure.
FIGS. 4 and 5 illustrate certain modifications to the fuel system
described above in conjunction with FIG. 1. Comparing FIGS. 4 and 5
to FIG. 1, it can be seen that conduit 96 in FIG. 1 has been
removed and its basic function is performed by conduit 300 in the
embodiments of the present invention shown in FIGS. 4 and 5. In
addition, the outlet 302 of the regulator 130 is now connected to
conduit 82 by conduit 304. In addition, orifice 306 is provided
within conduit 304 as shown in FIGS. 4 and 5. The embodiments shown
in FIGS. 4 and 5 differ from each other in the specific manner in
which the outlet flow from regulator 130 is directed into the
reservoir 10. Those differences will be described in greater detail
below.
In addition, dimension h is specifically shown in FIGS. 4 and 5. As
discussed above, the magnitude of dimension h determines the size
of the ullage in combination with other variables. Since the second
fuel pump 22 will draw vapor through the secondary opening 62 in
preference to drawing liquid through the primary opening 60, if
vapor is available at the secondary opening, the position of the
secondary opening 62 will play a significant role in the
determination of the size of the ullage. In a preferred embodiment
of the present invention, the diameter of the orifice, or secondary
opening 62, is 0.036 inches and the diameter of the primary opening
60 is 0.25 inches. These particular dimensions are satisfactory in
the preferred embodiments of the present invention described above,
but it should be clearly understood that alternative magnitudes can
be selected in other applications of fuel systems, depending on the
sizes, positions, and operating characteristics of the various
components.
The outlet 302 of the regulator 120, in FIG. 4, is connected to
conduit 304 and to conduit 310 which is provided with a check valve
312 as shown. The primary function of check valve 312 is to control
the direction of flow through conduit 310. In various embodiments
of the present invention, the operating characteristic of check
valve 312 can be selected to open at a pressure of between 70 kPa
and 200 kPa. The orifice 306 and check valve 312 work in
cooperation with each other to deliver fuel from the regulator 130
back to the reservoir 10 in a controlled manner. When the relative
pressures within the conduits and reservoir urge a fuel flow from
outlet 302 of the regulator 130 toward conduit 82, the orifice 306
controls the rate of that flow so that it does not exceed the
capabilities and operating characteristics of the first fuel pump
21.
With continued reference to FIG. 4, it should be noted that all of
the fuel entering the second inlet 32 of the second fuel pump 22
must flow through the second inlet conduit 52. This characteristic
differs from the embodiment shown in FIG. 1 which also can provide
a flow of fuel from the outlet of the regulator 130 directly to the
second inlet 32 of the second fuel pump 22.
FIG. 5 differs from the embodiment shown in FIG. 4 by providing a
direct connection between the outlet 302 of regulator 130 and the
second inlet 32 of the second fuel pump 22. That connection allows
fuel flow through check valve 313 when the relative magnitudes of
pressure at the second inlet 32 and within conduit 304 allow this
direction of flow. Orifice 306 serves a similar purpose to that
described above in conjunction with FIG. 4. As can be seen in FIG.
5, conduit 304 is connected in fluid communication with both the
second inlet conduit 52 and conduit 304, with check valve 313
disposed therebetween.
In both FIGS. 4 and 5, a check valve 320 is disposed in conduit 82
in order to govern the direction of flow of fuel through conduit
82. Check valve 320 assures that fuel flowing through conduit 304
from the regulator 130 will pass through the first heat exchanger
71 and not flow toward the first outlet 41 of the first pump
21.
Comparing FIGS. 4 and 5 to FIG. 1, it can be seen that conduit 96
shown in FIG. 1 is not present in FIG. 4 or 5. The basic function
performed by conduit 96 in the fuel system of FIG. 1 is performed
by conduit 300 which is shown connected to conduit 82 at a point
within the reservoir 10 and above the first outlet 41.
With continued reference to FIGS. 4 and 5, it should be understood
that the modifications to FIG. 1 which are represented in FIGS. 4
and 5 relate most specifically to the operational condition that
occurs when the fuel in fuel tank 80 is depleted and no longer
available to the first pump 21. Under that condition, it is likely
that some amount of fuel will continue to be available within the
reservoir 10 for provision to the fuel rail 138. Under this
condition, the first pump 21 can be operated with no liquid passing
through it. This can potentially result in damage to the first pump
21. The configuration of components described above in conjunction
with FIGS. 4 and 5 are intended to address this circumstance.
In a preferred embodiment of the present invention, regulator 130
is selected to have an operating pressure of approximately 350 kPa,
regulator 94 is selected to have an operating pressure of
approximately 70 kPa, check valve 312 is selected to have an
operating pressure of approximately 70 kPa to 200 kPa, check valve
320 is selected to have an operating pressure of less than 70 kPa
and orifice 306 is selected to allow a minimal flow of fluid
through conduit 304 with a purpose of providing sufficient flow of
liquid fuel to the first pump 21 to avoid allowing it to run under
completely dry conditions. Orifice 306 is sized to also avoid a
large flow of liquid fuel through conduit 304 which would
potentially exceed the capability of the first pump 21. The
embodiments shown in FIGS. 4 and 5 include modifications, as
described above, which are intended to be beneficial under
circumstances where the fuel tank 80 is depleted of fuel. Under
those circumstances, the fuel system in FIG. 1 could be considered
less than optimal in certain applications and under certain
conditions.
As described above, it can be seen that a marine engine fuel
system, made according to the preferred embodiments of the present
invention, comprises a reservoir 10 configured to contain a
quantity of fuel 12, a first fuel pump 21 having a first inlet 31
and a first outlet 41, a first inlet conduit 51 connected in fluid
communication with the first inlet 31, a second fuel pump 22 having
a second inlet 32 and a second outlet 42, and a second inlet
conduit 52 connected in fluid communication with the second inlet
32. In preferred embodiments of the present invention, the first
and second fuel pumps are disposed within the reservoir 10.
In a preferred embodiment of the present invention, the first inlet
conduit 51 is connected in fluid communication with a fuel tank 80
of a marine vessel and the first outlet 41 is connected in fluid
communication with the liquid fuel 12 within the reservoir 10. The
second inlet conduit 52 is connected in fluid communication with
the reservoir 10 and the second outlet 42 is connected in fluid
communication with the fuel rail 138. A primary opening 60 is
located at a distal end 150 of the second inlet conduit 52 and the
secondary opening 62 is an orifice located between the primary
opening 60 and the second inlet 32. The second inlet conduit 52 is
positioned to dispose the primary opening 60 within liquid fuel 12
and to dispose the secondary opening 62 in fluid communication with
the vaporous fuel when both liquid and vaporous fuel exist within
the reservoir 10. The second inlet conduit 52 is positioned, in a
preferred embodiment of the present invention, to dispose the
primary opening 60 closer to the second outlet 42 than to the
second inlet 32.
In a preferred embodiment of the present invention, it further
comprises a water pump 66, a first heat exchanger 71 having a first
water circuit which is connected in fluid communication with the
water pump 66 and disposed in thermal communication with a first
fuel circuit, and a second heat exchanger 72 having a second water
circuit which is connected in fluid communication with the water
pump 66 and disposed in thermal communication with a second fuel
circuit. The first fuel pump is connected in fluid communication
with the first fuel circuit and the second fuel pump is connected
in fluid communication with the second fuel circuit. The first
water circuit is disposed in thermal communication between the
first fuel circuit and the quantity of fuel 12 and the second water
circuit is disposed in thermal communication between the second
fuel circuit and the quantity of fuel 12 within the reservoir 10.
The first and second heat exchangers, 71 and 72, are disposed
within the reservoir 10 in a preferred embodiment of the present
invention. The first inlet conduit 51 is connected in fluid
communication with the fuel tank 80 of a marine vessel, the first
outlet 41 is connected in fluid communication with the reservoir 10
and the second outlet 42 is connected in fluid communication with a
fuel rail 138. The fuel system in a preferred embodiment of the
present invention is configured to inhibit fuel from flowing into
the first inlet 31 after it has flowed into the quantity of fuel 12
within the reservoir 10. In addition, the fuel system in a
preferred embodiment of the present invention is configured to
inhibit fuel from flowing into the quantity of fuel 12 within the
reservoir 10 after it has flowed out of the second outlet 42.
Although the present invention has been described in particular
detail and illustrated to show several embodiments, it should be
understood that alternative embodiments are also within its
scope.
* * * * *